Do you have a marketing budget? That will help you separate the 'possible' from the 'probable'.
Bear in mind that you don't need leads; you need customers. If you just want leads, go to the library and get a local business directory. That'll have lots of names, positions and telephone numbers - there's your leads, now hit the phone and call them.
If you want customers, the first thing you should do is define who your customer is - and who he isn't. For example, we get a lot of calls from people who have an idea for starting a business, and want us to develop their website. We pass on those - our customer profile is a small/medium marketing agency with third-party clients.
We know who we want to contact, so we go to the places they congregate. If you want to hunt ducks, you go to a duckpond, not a local zoo; if you want to find a lion, don't bother looking around the duckpond. Guess what you'll find at a local Chamber of Commerce?
Talk to your customers about things that interest them - giving your spin on it, of course. Get involved in the general conversation, get known for being the expert in your field, and the customers will come.